SACRAMENTO — (CNN) Wildfires engulfing parts of California could intensify Monday, with gusty winds potentially fanning fires caused by lightning strikes.

More than 9,300 firefighters are now battling at least 21 wildfires, according to the California Department of Forestry and Fire Protection, or Cal Fire.

The largest inferno, the Rocky Fire, has already incinerated 54,000 ares in three counties. As of Sunday night, it was only 5% contained and was feeding on the state’s drought to grow, Cal Fire spokesman Daniel Berlant said.

“This has been a very fast-moving wildfire with the dry conditions, and the weather not really cooperating with us over the past week,” Berlant told CNN affiliate KCRA.

The Rocky Fire was burning in Lake, Yolo and Colusa counties northwest of Sacramento. More than 12,100 people in more than 5,100 structures were under some type of evacuation order or advisory as of Sunday afternoon, according to Cal Fire.

Almost 2,000 fire personnel, 180 engines, four air tankers and 19 helicopters are battling that blaze.

Across the state, more than 134,000 acres have been torched by the ongoing fires, according to Cal Fire.

Lightning has helped fuel the flames. There have been thousands of lighting strikes over the past several days, igniting hundreds of small wildfires in the northern part of the state.

And the accompanying thunderstorms have produced little or no rain, Berlant said.

Most of the region will have stronger winds Monday, which could fan any lightning strikes from over the weekend, Cal Fire said.

Nighttime typically allows firefighters to make headway against wildfires because humidity will go up and fire activity will die down, but that hasn’t been the case with the Rocky Fire, Berlant said.

“This fire was very active throughout the night,” he told KCRA. “It was really burning very fast, all the way up into the late hours, so unfortunately we’re really not getting a break.”

California Gov. Jerry Brown declared a state of emergency Friday, mobilizing the National Guard to support the disaster response.

The U.S. Forest Service said David Ruhl, a father of two from Rapid City, South Dakota, died fighting the Frog Fire in Northern California’s Modoc National Forest near Adin.

Rescuers found Ruhl’s body Friday morning, the Forest Service said. His death remains under investigation.

The fires vary in size. The White Fire in Santa Barbara County is about 50 acres, and the deadly Frog Fire has consumed at least 3,900 acres since it was spotted Thursday and is just 4% contained. The recently snuffed-out Lake Fire in San Bernandino County burned more than 31,000 acres before it was contained.

Cal Fire says most of the fires are more than 60% contained. But the land damage has been substantial in some cases. Fires in Southern California’s San Bernardino County and Northern California’s Alpine County have incinerated nearly 50,000 acres.

California’s record-setting drought has “turned much of the state into a tinderbox,” Brown said.

Temperatures in Sacramento and other areas of Northern California, where many of the fires are located, have topped 100 degrees recently.

Authorities reported strides in two other fires: the Willow Fire northeast of North Fork in the Sierra National Forest and the Cabin Fire east of Porterville in the Sequoia National Forest.

The Willow Fire was 60% contained, and firefighters made “good progress” with a controlled-burn operation intended to deprive the blaze of more fuel, the South Central Sierra Interagency Incident Management Team said.

“Air resources will support ground crew as needed (as) soon as smoke conditions clear and allow for safe aerial operations,” the team said.

Evacuation orders remain in effect for those around the fire, which has already consumed more than 5,600 acres.

The Cabin Fire, which has burned 2,600 acres since mid-July, remained relatively calm, but was only 2% contained, according to a news release from the Sequoia National Forest.

Neither the Willow nor the Cabin fires has destroyed any structures, but six people have been injured in the Willow Fire.

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